Swarming Hedgehog Robots to Explore Space

We've written about several different robot swarms, such as the team that played Beethoven, another group that danced to light and music at Cannes, and a third that's worked as a construction gang. A new swarm from Stanford University, working with NASA's Jet Propulsion Laboratory and the Massachusetts Institute of Technology, joins a different class of robots that are helping to explore space.

The swarm consists of a mother craft described as the size of a coffee table (does anyone still have those?), and smaller rovers that look like white spheres with all-over Mohawks, measuring just under 20 inches in diameter. The Stanford-led team is developing the mothership-rover system to explore moons and asteroids. The mothership would carry one or more rovers, dubbed "hedgehogs," to their destination, disgorge them, and orbit the moon or asteroid while the hedgehogs do their jobs. All craft would be powered by solar panels.

A robot swarm has been developed by Stanford University as a mothership-sphere system to explore planetary moons and asteroids. (Source: Dept. of Aeronautics and Astronautics, Stanford University)

The hedgehogs would gather detailed data, such as using microscopes to measure fine crevices and fissures in the terrain. Meanwhile, the mothership will not remain idle: It might conduct large-scale measurements, such as determining the surface concentration of chemical elements and compounds.

Hedgehog rover craft have been designed as spheres to overcome the challenges of exploring bodies with much lower gravity than a planet's. The first mission will be to Mars's moon Phobos. Its gravity is 1,000 times weaker than that of Mars. In that kind of environment, wheels are likely to lose traction, so team members designed the rovers to rely on airborne motion.

Inside each hedgehog are three rotating flywheels, each aimed in a different direction. The spinning disks' inertial forces let the spheres move with precision in an environment where traditional rovers would bounce or float uncontrollably. By quickly accelerating, the acrobatic spheres can hop for long-range ground coverage. Spinning them faster makes them bound. A slight acceleration makes them tumble, used for fine movements.

The mothership, called the Phobos Surveyor, and hedgehogs will work closely together to initiate and continue the mission. After launching the first sphere, the Phobos Surveyor and the sphere jointly determine its location and orientation, and then map its trajectory. As the hedgehog relays data back to the Surveyor, the mothership in turn sends it to scientists on Earth. Their analysis determines whether up to four or five more hedgehogs will be released, where they will go, and what information they will gather. An entire mission could last two to three years.

The researchers, led by Marco Pavone, an assistant professor in Stanford's Department of Aeronautics and Astronautics, have already constructed two generations of rover prototypes. They expect to test the third-generation hedgehog next summer in a test site that will mimic low-gravity conditions as closely as possible. In two to four years tests will be done of the Phobos Surveyor.

In March, the team will present a paper describing the project at the 2012 IEEE Aerospace Conference in Big Sky, Montana. A presentation can be accessed here and a detailed project report here.

They already have 'space custodians' according to the anime Planetes. Then again, with the destruction of the space shuttle Explorer and the Hubble Space Telescope in Gravity, space hedgehogs would be ideally suited for the task of cleaning up the high-speed debris.

You are behind the times, Scott. I, myself, have saved the galaxy numerous times. We space warriors don't have time to clean up space trash or save the environment when there are so many forms of intelligent space monsters trying to invade the earth. It takes all our waking hours to keep humans safe.

You are behind the times, Scott. I, myself, have saved the galaxy numerous times. We space warriors don't have time to clean up space trash or save the environment when there are so many forms of intelligent space monsters trying to invade the earth. It takes all our waking hours to keep humans safe.

Great idea, Willliam. What we need is to harness the excess energy and time of gamers to clean space debris, consume poisons from the environment, optimize freight routings and a host of logistic endeavors. Just turn them into games and the problems would be solved in no time.

I think that I detect a lack of information about what is needed to track a chunk of debris traveling at 1700MPH, and perhaps a need to investigate the kinetics involved with deflecting such a particle.

For a much simplified example, imagine attempting to defrlect a golf ball that has just been hit by a strong golfer using a heavier driver club. There would be quite a few challenges.

Come to think of it some technology may have been inspired by fantasy novels, as well as sci-fi. For instance, I'm re-reading Tolkien's Lord of the Rings, and the Palantir might be seen as a wireless video-conferencing system.

You are spot on, freisl. I suggest we take it another step and add Crowdsourcing and Gamification. I say we have a company launch a low-orbit satellite that contains a fantastically-large supply of Hedgehog Sweepers that can be controlled from a smartphone app here on Earth. Users would download the app and then aim and control the trajectory of a Hedgehog Sweeper to nudge a piece of space junk into the atmosphere using an app having game play similar to Angry Birds. In-app upgrade purchases of additional sensors and controls along with advertising would help to defray the costs of the entire program while performing a needed service to humanity's future endeavors in space. I think I would even be willing to pay $2.99 for the Angry Hedgehogs app...

There are several serious challenges relative to cleaning up space debris, and several of those challenges are quite daunting.

First, those chunks of whatever are all orbiting quite rapidly, and they weigh quite a few pounds. So intercepting them is a lot like catching large bullets. Consider what it would take to catch a baseball moving at 1000MPH. Many of the fragments are that heavy, and moving quite a bit faster.

Next, these chunks of junk are in various orbits, they are not just sitting there waiting to be captured. And when they are caught, consider the amount of energy transferred. So after acquiring one of these targets, catching it could be very exciting. Then there is the question of what to do with it once you have it. At least one sattelite was designed to capture one item and then burn up during re-entry. Quite effective but very expensive.

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.